Gypsum board, also known as sheetrock or drywall, is widely used in the construction, remodeling and repair of residential homes, commercial buildings, and the like. Drywall is available in various sizes, such as 4.times.8 foot or 4.times.12 foot sheets that are typically 1/2 or 5/8 inches thick. The drywall is generally attached to the wood or steel studs of the infrastructure by nails or screws. Because joints are formed when the drywall is hung, these joints must be covered using drywall joint compound and drywall tape in order to provide an acceptable finish before paint or wallpaper is applied to the walls.
Conventional drywall joint compound is available in dry powder or "ready-mixed" form. Commonly available ready-mixed drywall joint compound products include SHEETROCK.RTM. All Purpose Joint Compound, which is available from United States Gypsum Company of Chicago, Ill., and GOLD BOND.RTM. All Purpose Ready Mix Joint Compound, which is available from National Gypsum Company of Charlotte, N.C. SHEETROCK.RTM. brand joint compound consists primarily of the following ingredients: (1) limestone, chemically known as calcium carbonate (CaCO.sub.3), or dolomite (CaMg(CO.sub.3).sub.2) or gypsum (CaSO.sub.4.2H.sub.2 O); (2) water; (3) mica (silicates of varying chemical composition); (4) ethylene-vinyl acetate polymer or vinyl acetate polymer; (5) attapulgite clay (hydrated aluminum silicates); and (6) trace amounts of vinyl acetate monomer, acetaldhyde and crystallized silicon dioxide (quartz). United States Gypsum SHEETROCK.RTM. may also include talc (a hydrous magnesium silicate) and pyrophyllite. National Gypsum GOLD BOND.RTM. brand joint compound consists primarily of the following ingredients: (1) calcium carbonate; (2) quartz; and (3) water. GOLD BOND.RTM. may also include mica, talc, perlite, attapulgite clay, various polymers and various monomers.
The conventional procedure for finishing drywall joints is well known in the art.
Typically, the ready-mixed joint compound already contains the proper amount of water. If not, water can be added to the drywall joint compound to produce the desired consistency for a particular application. Regardless, the joint compound should be stirred vigorously before applying it to the drywall. A 4 to 6 inch joint finishing knife is used to place a first coat of joint compound in the joint. Drywall tape is placed over the joint and pressed into the joint compound using the knife. Usually, about 24 hours must be allowed for the first coat to dry thoroughly. A second coat of joint compound is applied over the first coat that extends a few inches beyond the edges of the tape on both sides. Again, the second coat usually requires about 24 hours to dry thoroughly. A 10-inch joint finishing knife is then used to apply a third and final coat. The total width of the third coat is typically about 12-14 inches. After the final coat dries, it is sanded to a smooth finish and any dust is wiped off prior to painting or applying wallpaper. Nail holes are also filled in with the joint compound and sanded, as necessary.
A major disadvantage of the conventional method for finishing drywall joints is the extended time that is required for the drywall joint compound to dry thoroughly. Because of the 24-hour drying time required between coats, the overall time needed to finish drywall joints is significant, typically two or more days. If necessary, sanding the final coat of the drywall joint compound further increases the overall time needed to finish the drywall joints. Additionally, sanding creates a potential health hazard due to the significant amount of dust generated during the sanding process. Therefore, a method of reducing the drying, or curing, time of the drywall joint compound and of eliminating the need for sanding the final coat would be a great improvement over the art. Such a method would reduce drywall construction labor costs and reduce overall drywall construction time. The method would be especially valuable in remodeling and repairing buildings which must be occupied during the remodeling or repair process.